31:T72e,

Aiming to fully fund yearly tuition of $${Inputs.bind(Tangle({minWidth: "3em", max: 100000, step: 100}), viewof tuition)}, adjusted for tuition inflation, for each of ${Inputs.bind(Tangle({min: 0, minWidth: ".8em"}), viewof college_years)} years for all of your ${kid_faces.slice(0, Object.keys(kids).length)} (${Object.keys(kids).length}) kids with ${((1-utma_fraction/100)*100).toFixed(0)}% of the total in 529 plan (transferrable, but only for college) and the other ${Inputs.bind(Tangle({min: 0, minWidth: "1.3em", max: 100}), viewof utma_fraction)}% in UTMA savings by child.

${name.slice(0, 1).toUpperCase()}${name.slice(1, 100)} starts/started preschool in ${kids[name].preschool_start}, college in ${kids[name].preschool_start + precollege_school_years}, so needs ${money(utma_fraction / 100 * contributions_per_kid[i][current_year-min_start_year].balance)} saved by end of this year (${current_year}) in the UTMA in order to pay the full cost of college, ${money(d3.sum(contributions_per_kid[i], d => d.withdrawal))}, by the end of ${kids[name].preschool_start + precollege_school_years + college_years - 1}.` )) }

and a total in 529 savings of ${money(target_529)}. In total, that will mean saving enough for ${money(d3.sum(contributions_per_kid.map(e => d3.sum(e, d => d.withdrawal))))} through the last year the last kid is in college (the ${max_end_year}-${max_end_year+1} school year).

Note, all in today's dollars, adjusting returns and college tuition inflation for inflation. Also adjusted your contributions to increase with inflation, unless you check the box to make a flat contribution.

32:T429,viewof kids_dynamic = { const ui = view` ${["elements", [ Inputs.range([1990, 2022], { value: 2017, step: 1, label: "Kid born in:" }), Inputs.toggle({ value: false, label: "Born before school cutoff" }), Inputs.range([1990, 2022], { value: 2019, step: 1, label: "Kid born in:" }), Inputs.toggle({ value: true, label: "Born before school cutoff" }), Inputs.range([1990, 2022], { value: 2021, step: 1, label: "Kid born in:" }), Inputs.toggle({ value: true, label: "Born before school cutoff" }) ], d => d]}

${Inputs.button("Add kiddo", { reduce: () => { ui.value.elements.push(Inputs.range([1990, 2022], { value: 2017, step: 1, label: "Kid born in:" })); ui.value.elements.push(Inputs.toggle({ value: true, label: "Born before school cutoff" })); } })} ${Inputs.button("Remove kiddo", { reduce: () => { ui.value.elements.pop(); ui.value.elements.pop(); } })}

`; return ui; }33:Ta86,compute_contributions = function(d, j, since_birth, yearend_savings_, kid_balances_) { const start_year = d.birth_year; const college_start = d.preschool_start + precollege_school_years; const end_year = college_start + college_years - 1; // const total_college_cost = tuition * college_years; const total_college_cost = d3.sum(tuition_inflated.slice(college_start-min_start_year, end_year-min_start_year+1), d => d.tuition); const yearly_contribution = total_college_cost / (end_year - start_year + 1); var tmp = Array(max_end_year - min_start_year + 1); var balanced = false; var multiplier = 1; var heat = .9; var iteration = 0; const max_iterations = 100 while (!balanced & (iteration < max_iterations)) { // console.log('iteration', iteration) for (var i=0; i < tmp.length; i++) { const cal_year = i + min_start_year; const year_diff = cal_year - current_year; const total_inflation = Math.pow(1 + inflation_rate/100, year_diff); const total_deflation = Math.pow(1 - inflation_rate/100, year_diff); const inflation_adjusted_contribution = contributions_match_inflation ? yearly_contribution : total_deflation * yearly_contribution; const started_college = cal_year >= college_start; // this will turn during the cal year they start const finished_college = cal_year > end_year; // this will turn on the year they graduate const in_college = (started_college) & (!finished_college); const born = cal_year >= d.birth_year; const age = born ? cal_year - d.birth_year : 0; tmp[i] = { name: Object.keys(kids)[j], year: cal_year, age_last_bday: age, yearly_contribution: ((cal_year > current_year) | (since_birth & born)) & (!finished_college) ? inflation_adjusted_contribution * multiplier : 0, withdrawal: in_college ? tuition_inflated[i].tuition : 0 } if ((cal_year == current_year) & !since_birth) { tmp[i].yearly_contribution = yearend_savings_ * kid_balances_[j]; } tmp[i].monthly_contribution = tmp[i].yearly_contribution / 12; tmp[i].net = tmp[i].yearly_contribution - tmp[i].withdrawal; tmp[i].balance = (1 + (net_return / 100)) * (i > 0 ? tmp[i-1].balance + tmp[i].net : tmp[i].net); tmp[i].yearly_contribution_inflated = tmp[i].yearly_contribution * total_inflation; } if (Math.abs(tmp[tmp.length-1].balance) > 20) { if (tmp[tmp.length-1].balance > 0) { multiplier = multiplier * (1 - heat); } else { multiplier = multiplier * (1 + heat); } heat = heat * .9; } else { balanced = true; } iteration++; } return tmp; }34:[] 2f:{"title":"College funding for kids","cells":[{"id":46,"value":"

College funding for kids

\n","pinned":false,"hidden":false,"mode":"html"},{"id":257,"value":"vis = Plot.plot({\n title: \"Combined account balance\",\n subtitle: \"Inflation adjusted.\",\n marginLeft: 50,\n width: 900,\n height: 200,\n marks: [\n Plot.barY(\n [].concat.apply([], contributions_per_kid),\n {\n x: \"year\", \n y: d => d.balance, \n fill: \"name\",\n title: d => `${d.name}\\nContribution: ${money(d.yearly_contribution)}\\nWithdrawal: ${money(d.withdrawal)}\\nInflated contribution: ${money(d.yearly_contribution_inflated)}`\n }\n )\n ]\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":850,"value":"$31","pinned":false,"hidden":false,"mode":"html"},{"id":125,"value":"$32","pinned":false,"hidden":false,"mode":"ojs"},{"id":85,"value":"viewof tuition = Inputs.range([umass_instate/2, umass_instate*3], {step: 100, label: \"Tuition ($)\", value: umass_instate, format: d => d})","pinned":false,"hidden":false,"mode":"ojs"},{"id":106,"value":"viewof utma_fraction = Inputs.range([0, 100], {step: 1, label: \"Fraction in UTMA (%)\", value: 66.6})","pinned":false,"hidden":false,"mode":"ojs"},{"id":356,"value":"viewof return_rate = Inputs.range([0, 7], {step: .1, label: \"Investment Return Rate (%)\", value: 3})","pinned":false,"hidden":false,"mode":"ojs"},{"id":369,"value":"viewof inflation_rate = Inputs.range([0, 7], {step: .1, label: \"Inflation Rate (%)\", value: 3})","pinned":false,"hidden":false,"mode":"ojs"},{"id":360,"value":"viewof tuition_inflation = Inputs.range([0, 15], {step: .1, label: \"Tuition Inflation Rate (%)\", value: 5})","pinned":false,"hidden":false,"mode":"ojs"},{"id":363,"value":"viewof contributions_match_inflation = Inputs.toggle({label: \"Match contributions to inflation rate\", value: true})\n// otherwise, flat like a mortgage","pinned":false,"hidden":false,"mode":"ojs"},{"id":517,"value":"Savings that you will achieve by year end ${Inputs.bind(Tangle({minWidth: \"2em\", step: 1, format: d => d}), viewof current_year)}, whether or not it matches the target total ${money(total_contributions_current_year)}:","pinned":false,"hidden":false,"mode":"md"},{"id":512,"value":"viewof yearend_savings = Inputs.text({label: \"Current savings ($)\", value: total_contributions_current_year})","pinned":false,"hidden":false,"mode":"ojs"},{"id":533,"value":"Given kids' ages, to we would split the ${money(yearend_savings)} among the 529 account ${money(target_529_current)}, and for each kid's UTMA ${kid_balances.map(d => money(d * target_UTMA_current)).join(\", \")}, respectively. If you can't catch up to the amounts as if you'd started when kids were born, get as close as you can, and either try next to catch up or at least hit the adjusted targets.","pinned":false,"hidden":false,"mode":"md"},{"id":666,"value":"To fully catchup and the given numbers above, given that you're already balanced as above, you will need to contribute in total ${money(catchup_total)}, with a 529 contribution of ${money(catchup_529)}, a total UTMA contribution of ${money(catchup_UTMA)} and per-kid UTMA contributions of ${kid_balances.map(d => money(d * catchup_UTMA)).join(\", \")}.\n\nThis year's scheduled contribution, if you were on track last year, is ${contribution_narrative(current_year, contributions_per_kid)}.\n\nNext year's scheduled contribution is ${contribution_narrative(current_year+1, contributions_per_kid, true)}.","pinned":false,"hidden":false,"mode":"md"},{"id":670,"value":"Withdrawals scheduled this year are ${contributions_per_kid.map(d => money(d[current_year - min_start_year].withdrawal)).join(\", \")} and next year are ${contributions_per_kid.map(d => money(d[current_year + 1 - min_start_year].withdrawal)).join(\", \")}.","pinned":false,"hidden":false,"mode":"md"},{"id":644,"value":"Next year, the adjusted target, given current savings (assuming it's already balanced as above), is to put a total of ${contribution_narrative(current_year+1, contributions_per_kid_starting_now, true)}.","pinned":false,"hidden":false,"mode":"md"},{"id":504,"value":"","pinned":false,"hidden":false,"mode":"md"},{"id":333,"value":"Plot.plot({\n title: \"Contributions by year\",\n subtitle: \"Inflation adjusted.\",\n marginLeft: 50,\n width: 900,\n height: 200,\n marks: [\n Plot.barY(\n [].concat.apply([], contributions_per_kid),\n {\n x: \"year\", \n y: d => d.yearly_contribution,\n fill: \"name\",\n title: d => `${d.name}\\nContribution: ${money(d.yearly_contribution)}`\n }\n )\n ]\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":631,"value":"Plot.plot({\n title: \"Combined account balance\",\n subtitle: `Inflation adjusted, starting with ${money(yearend_savings)} saved/contributed this year.`,\n marginLeft: 50,\n width: 900,\n height: 200,\n marks: [\n Plot.barY(\n [].concat.apply([], contributions_per_kid_starting_now),\n {\n x: \"year\", \n y: d => d.balance, \n fill: \"name\",\n title: d => `${d.name}\\nContribution: ${money(d.yearly_contribution)}\\nWithdrawal: ${money(d.withdrawal)}`\n }\n )\n ]\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":641,"value":"Plot.plot({\n title: \"Contributions by year\",\n subtitle: `Inflation adjusted, starting with ${money(yearend_savings)} saved/contributed this year.`,\n marginLeft: 50,\n width: 900,\n height: 200,\n marks: [\n Plot.barY(\n [].concat.apply([], contributions_per_kid_starting_now),\n {\n x: \"year\", \n y: d => d.yearly_contribution,\n fill: \"name\",\n title: d => `${d.name}\\nContribution: ${money(d.yearly_contribution)}`\n }\n )\n ]\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":173,"value":"# Code\n\nFor starters, I chose to have tuition be the same for all kids. Of course we could let it be different per kid, but at least for me, it's a bit early to do that!\n\nCurrent year defaults to local current timestamp, with year of ${this_year}. You can adjust it:","pinned":false,"hidden":false,"mode":"md"},{"id":612,"value":"viewof current_year = Inputs.range([this_year-10, this_year+10], {step: 1, label: \"Current year\", value: this_year})","pinned":false,"hidden":false,"mode":"ojs"},{"id":616,"value":"this_year = (new Date()).getFullYear()","pinned":false,"hidden":false,"mode":"ojs"},{"id":741,"value":"The narrative for how much to contribute this year and next is repetitive, so here's a function to make it:","pinned":false,"hidden":false,"mode":"md"},{"id":676,"value":"contribution_narrative = function(year, contributions, inflate=false) {\n const contributions_per_kid = contributions.map(d => inflate ? d[year + 1 - min_start_year].yearly_contribution_inflated : d[year + 1 - min_start_year].yearly_contribution);\n const total_contribution = d3.sum(contributions_per_kid);\n const target_529 = (1 - (utma_fraction / 100) ) * total_contribution;\n const target_UTMA = total_contribution - target_529;\n const target_UTMA_per_kid = contributions_per_kid.map(d => money(d / total_contribution * target_UTMA));\n return `total contributions of ${money(total_contribution)} with 529 contribution of ${money(target_529)}, total UTMA contribution of ${money(target_UTMA)}, and per kid's UTMA of ${target_UTMA_per_kid.join(\", \")}`\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":704,"value":"catchup_529 = catchup_total - catchup_UTMA","pinned":true,"hidden":false,"mode":"ojs"},{"id":701,"value":"catchup_UTMA = catchup_total * (utma_fraction / 100)","pinned":true,"hidden":false,"mode":"ojs"},{"id":695,"value":"catchup_total = d3.max([total_contributions_current_year - yearend_savings, 0])","pinned":true,"hidden":false,"mode":"ojs"},{"id":597,"value":"target_529_current = (1 - (utma_fraction / 100) ) * yearend_savings","pinned":true,"hidden":false,"mode":"ojs"},{"id":594,"value":"target_UTMA_current = yearend_savings - target_529_current","pinned":true,"hidden":false,"mode":"ojs"},{"id":570,"value":"target_UTMA = total_contributions_current_year - target_529","pinned":true,"hidden":false,"mode":"ojs"},{"id":567,"value":"target_529 = (1 - (utma_fraction / 100) ) * total_contributions_current_year","pinned":true,"hidden":false,"mode":"ojs"},{"id":660,"value":"nextyear_withdrawals_by_kids = contributions_per_kid_starting_now.map(d => d[current_year + 1 - min_start_year].withdrawal)","pinned":true,"hidden":false,"mode":"ojs"},{"id":655,"value":"nextyear_adjusted_contribution_by_kids = contributions_per_kid_starting_now.map(d => d[current_year + 1 - min_start_year].yearly_contribution)","pinned":true,"hidden":false,"mode":"ojs"},{"id":649,"value":"nextyear_target_by_kids = contributions_per_kid.map(d => d[current_year + 1 - min_start_year].balance)","pinned":true,"hidden":false,"mode":"ojs"},{"id":663,"value":"thisyear_withdrawals_by_kids = contributions_per_kid_starting_now.map(d => d[current_year - min_start_year].withdrawal)","pinned":true,"hidden":false,"mode":"ojs"},{"id":552,"value":"yearend_target_by_kids = contributions_per_kid.map(d => d[current_year-min_start_year].balance)","pinned":true,"hidden":false,"mode":"ojs"},{"id":559,"value":"kid_balances = yearend_target_by_kids.map(d => d / total_contributions_current_year)","pinned":true,"hidden":false,"mode":"ojs"},{"id":536,"value":"total_contributions_current_year = d3.sum(yearend_target_by_kids)","pinned":true,"hidden":false,"mode":"ojs"},{"id":478,"value":"viewof college_years = Inputs.input(4)","pinned":true,"hidden":false,"mode":"ojs"},{"id":761,"value":"Function to format money values:","pinned":false,"hidden":false,"mode":"md"},{"id":73,"value":"money = d3.format(\"$,.0d\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":764,"value":"Parse the dynamic kids input:","pinned":false,"hidden":false,"mode":"md"},{"id":6,"value":"kids = {\n var tmp = {};\n for (var i=0; i d.birth_year)","pinned":true,"hidden":false,"mode":"ojs"},{"id":234,"value":"end_years = Object.values(kids).map(d => d.preschool_start + precollege_school_years + college_years - 1)","pinned":true,"hidden":false,"mode":"ojs"},{"id":733,"value":"kid_faces = [\"🧒\",\"🧒\",\"🧒\",\"🧒\",\"🧒\",\"🧒\",\"🧒\",\"🧒\"]","pinned":true,"hidden":false,"mode":"ojs"},{"id":220,"value":"max_end_year = d3.max(end_years)","pinned":true,"hidden":false,"mode":"ojs"},{"id":728,"value":"Inputs.table(tuition_inflated)","pinned":true,"hidden":false,"mode":"ojs"},{"id":390,"value":"tuition_inflated = {\n const net_tuition_inflation = tuition_inflation - inflation_rate;\n var tmp = Array(max_end_year - min_start_year + 1);\n for (var i=0; i < tmp.length; i++) {\n const cal_year = i + min_start_year;\n const year_diff = cal_year - current_year;\n tmp[i] = {year: cal_year, tuition: Math.pow(1 + net_tuition_inflation/100, year_diff) * tuition};\n }\n return tmp;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":719,"value":"viewof rows = Inputs.table(contributions_per_kid[0])","pinned":true,"hidden":false,"mode":"ojs"},{"id":198,"value":"contributions_per_kid = Object.values(kids).map((d, j) => compute_contributions(d, j, true, NaN, NaN))","pinned":true,"hidden":false,"mode":"ojs"},{"id":629,"value":"contributions_per_kid_starting_now = Object.values(kids).map((d, j) => compute_contributions(d, j, false, yearend_savings, kid_balances))","pinned":true,"hidden":false,"mode":"ojs"},{"id":804,"value":"net_return = return_rate - inflation_rate","pinned":true,"hidden":false,"mode":"ojs"},{"id":783,"value":"$33","pinned":true,"hidden":false,"mode":"ojs"},{"id":183,"value":"### Imports\n\nStanding on the shoulders of giants.","pinned":false,"hidden":false,"mode":"md"},{"id":24,"value":"require(\"d3\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":51,"value":"import { clone } from \"@mbostock/html-in-markdown\"","pinned":true,"hidden":false,"mode":"ojs"},{"id":116,"value":"import { view } from \"@tomlarkworthy/view\"","pinned":true,"hidden":false,"mode":"ojs"},{"id":770,"value":"import { Tangle } from \"@mbostock/tangle\"","pinned":true,"hidden":false,"mode":"ojs"},{"id":773,"value":"import { Plot } from \"@mkfreeman/plot-tooltip\"","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W34","stdlib":"1","titling":"auto"}