Your line 15000 is your Total income earned as of 2023 fiscal year.
To calculate Total Income for Tax Purposes, add:
income from employment and commissions
other employment income, including income from wage loss replacement plans
Old Age Security pension from T4A(OAS) slips
Canada Pension Plan or Quebec Pension Plan benefits from T4A(P) slips
other pensions or superannuation
eligible pension income transferred from spouse (see pension splitting)
Universal Child Care Benefit (UCCB) payments of $100 per month for each dependent child under 6 (claimed on the tax return of the lower income spouse)
employment insurance and other benefits from T4E slips
grossed-up Canadian dividends (see dividend tax credit)
interest and other investment income
net income from partnerships (limited or non-active partners only)
net rental income
current year taxable capital gains in excess of current year allowable capital losses, including gains from the sale of personal use property or listed personal property with a cost exceeding $1,000
taxable support payments received - see CRA Pamphlet P102 Support Payments and Income Tax Folio S1-F3-C3, Support Payments for information on when support payments are taxable (and deductible to the payer)
RRSP income from T4RSP slips
other income, including taxable scholarships, apprenticeship incentive grants, lump sum payments from pensions and deferred profit sharing plans, severance pay and retiring allowances, etc.
net income from self-employment (business, professional, commission, farming, and fishing)
Line 14700 other payments (included here, but deducted later, at Line 25000:
workers' compensation benefits from T5007 slip
social assistance payments
net federal supplements from T4A(OAS) slip
The total of the above is total income for tax purposes, line 15000 on the tax return.